Separation of propylene oxide from other hydrocarbons



United States Patent Ofice 3,464,897 Patented Sept. 2, 1969 3,464,897 SEPARATION OF PROPYLENE OXIDE FROM OTHER HYDROCARBONS John C. Jubin, Jr., Wallingford, Pa., assignor to Atlantic cyclohexane, hexyl cyclohexane and dimethyl cyclohexane can be used.

Optimum separations are obtained when the paratfin is present in an amount sufiicient to lower the relative volatilities of the hydrocal bons below 0.80. In most cases,

fflggfie g Phlladelphla a corporation of 5 parafiin concentrations ranging from 0.1 to 20 parts by No Drawing. Filed June 2, 1967, Ser. No. 643,063 weig p one P y Weight P py Oxide in the Int. Cl. B01d 3/34 feed are sufiicient. Preferably, the paraffin concentration US. Cl. 203--52 7 Claims ranges from 1 to 15 parts by weight per part propylene 10 oxide in the feed.

The fractional distillation is carried out under normal conditions. Preferably, the feed is introduced at point ABSTRACT OF THE DISCLOSURE near the bottom of the column and the paraffin intro- This invention relates to an improvement in the sepd=11ced at a point near the top of the column. Pressures aration of propylene oxide from other hydrocarbon com- 15 greater han atmospheric are suitable. The purified propounds which upon distillation exhibit boiling points pylene oxide is recovered overhead and a portion is reequal to or near that of propylene oxide, The improvecycled to the column to provide a reflux which prevents ment comprises distilling the mixture in the presence of the parafiin agent from distilling overhead. The bottoms an open chain or cyclic paraflin containing from 8 to 12 comprise the paraifin and the hydrocarbon impurities carbon atoms. The amount of parafiin normally ranges such as hexane, hexene, 2-methyl pentane, 4-methyl from about 0.1 to 20 parts by weight per one part propentcne-l, 4-methyl pentene-2, Z-methyl pentene-l and pylene oxide. 2-methyl pentene-Z. The bottoms can be subjected to an additional separation of paraflin from hydrocarbon impurities. 'Ihe paraflin can be then recycled to the column. Background of invention The following examples are given to illustrate specific embodiments of this invention and should not be con- In i epoxldatlon of Propylene to w stnued as limitations upon the scope of the invention. lous side products especlally those containing slx carbon atoms such as hexane, hexene and their isomers are Example I 21? liase fihli ii .ZfiZEZ SXii llfaiiilii iill A PmPYm feed was Prepared having the tional distillation is extremely difficult. With some com- 1Wmg c"mposltlon m p c nt by Weight. pounds azeotropes are formed which make economical Percent separations impossible. It has now been found that a Propylene OXlde 99-80 highly efficient separation can be obtained by adding to y Pentane 005 the mixture an open chain or cyclic parafiin as a distilla- 4-methyl pentene'l tion agent. This agent changes the volatility of the other y pentene'l (1-05 hydrocarbons relative to that of propylene oxide and thus y PeIIteIIe-Z makes an effective separation possible. The use of a parafiin distillation agent is operable over a wide range of 40 100-00 propylene oxide/hydrocarbon cencentrations including In each run a Portion of the feed was charged to a mixtures which eifher the Propylene oxide or the stirred vessel and heated to the temperature specified in drocarbon is the ma or component. Table I. The overhead line was heated to prevent re- It 15 f 9 1 mventlon to proYlde a method fiuxing and the overhead product was continually refor fractional dlstlllatlon of propylene oxlde to eifect a turned to the bottom of the vessel The temperature was seBamtion from other hydrocarbon? exhibiting boiling maintained for one hour at which time a sample of the Polnts equal to or near Propykine Oxldeoverhead was taken and analyzed by gas chromatograph. The invention is Pfaetieed y ffaetio'nany dlstllhng a In Runs 2-4 the procedure was repeated utilizing decane P py Oxide mixture in the Presence of all P Chain as a distillation agent. From an analysis of the overhead r cy i p r flin in an amo nt fii n to eff t a pstreams and the liquid remaining in the vessel, the fol- "\ration of propylene oxide from other hydrocarbons exlowing relative volatilities were determined.

TABLE I Relative volatility of hydrocarbon relative to propylene oxide Liquid temp, Weight per- 2-methy1 4-methyl 2-methyl 2 methyl Run No F. cent decane pentane pentene-l pentene-l pentene-2 95. 5 0 1. 20 1.13 0. 86 0.78 96. a 10 0. 9s 0. 96 0.70 0. 66 101. 0 34 0. so 0. 90 0. e1 0. 51 118.2 66 0. s3 0. 79 0. 34 0. 32

hibiting boiling points equal to or near propylene oxide. From the data in Table I the effect of the paraflin is The Pafafiill can be y Saturated p chain cyclic clearly shown by the change in relative volatility of the hydrocarbon containing from 8 to 12 carbon atoms. These various hydrocarbon impurities paraflins do not azeotrope with either the propylene oxide or the hydrocarbons. Preferably, the paraffin contains Example I1 l'rom 8 to 10 carbon atoms. For example, octane, isooc- 70 t-ane, nonane, decane, undecane, dodecane, ethyl cyclohexane, propyl cyclopentane, propyl cyclohexane, diethyl The following runs were conducted utilizing the feed and procedure of Example I.

Example III When the propylene oxide feed of Example I is mixed with other paraflins such as octane, nonane, dodecane, ethyl cyclohexane and butyl cyclohexane and distilled in accordance with the procedure of Example 1, similar results are obtained.

Example IV A propylene oxide feed contains Z-methyl pentane, 4-methyl pentene-l, 2-methyl pentene-l and 2-methyl pentene-2 all in concentrations of less than 0.2 weight percent each. This feed is heated and charged near the bottom of a distillation column in which octane is entering at a point near the top of the column. The weight ratio of octane to propylene oxide feed is about 12. The distillation is conducted at an elevated pressure such that the temperature is in excess of 200 F. and propylene oxide (99+ purity) is drawn off as overhead. A reflux equal to 1.8 times the amount of feed is maintained. The bottoms which comprise octane and the hydrocarbons are removed and further separated. The paraflin stream after the hydrocarbon impurities have been removed therefrom is then recycled to the distillation column.

I claim:

1. In the fractional distillation of propylene oxide from hydrocarbons containing six carbon atoms and exhibiting boiling points equal to or near propylene oxide, the improvement which comprises distilling the mixture in the presence of an open chain or cyclic paraffin containing from 8 to 12 carbon atoms and which does not form an azeotrope with the propylene oxide or hydrocarbons, said parafiin being added in an amount sufficient to lower the volatility of the hydrocarbons relative to the propylene oxide to below 0.8 and eifect a separation of propylene oxide from the hydrocarbons, the purified propylene oxide being recovered as overhead and the bottoms comprising said paraffin and hydrocarbons.

2. A method according to claim 1 wherein the amount of paraffin ranges from 1 to 15 parts per part propylene oxide in the feed.

3. A method according to claim 1 wherein the paraffin is an alicyclic compound.

4. A method according to claim 1 wherein the paraflin contains from 8 to 10 carbon atoms.

5. A method according to claim 1 wherein the paraflin is decane.

6. A method according to claim 5 wherein the paraffin is octane.

7. A method according to claim 1 wherein the hydrocarbons are selected from the group consisting of Z-methyl pentane, 4-methyl pentene-l, Z-methyl pentene-l, Z-methyl pentene-2 and mixtures thereof.

References Cited UNITED STATES PATENTS 3,039,940 6/1962 Prinz et al. 203-68 X 3,337,425 8/1967 Binning et al. 203-52 3,350,415 10/1967 Binning 260-3485 3,350,416 10/1967 Binning et al 260-3485 3,350,420 10/1967 Fariss 203-52 X 3,338,800 8/1967 Binning et a1 203-52 3,350,418 10/1967 Bowe et al. 203-52 X 3,350,419 10/1967 Null et al 260-3485 NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND, Assistant Examiner U.S. Cl. X.R.

Notice of Adverse Decision in Interference In Interference No. 97,594 involving Patent No. 3,464,897, J. C. J ubin, J r., SEPARATION OF PROPYLEN E OXIDE FROM OTHER HYDROCAR- BONS, final judgment adverse to the patentee was rendered Oct. 1, 1973, as to claims 1, 2, 3, 4, 6 and 7.

[Ojficial Gazette February 26, 1.974.] 

